This invention relates to methods of and apparatus for identifying faults in internal combustion engine cooling systems, and more particularly to such methods and apparatus which monitor cooling system heat capacity.
Temperatures inside an internal combustion engine""s combustion chambers can reach 4,500xc2x0 F. Only one half of an engine""s coolant capacity is held by an automobile""s radiator, nevertheless, the radiator must have the capacity to transfer 150,000 BTUs per hour to the atmosphere. This requires hundreds of gallons of coolant per hour to be circulated through an engine""s cooling system. In addition to cooling engines, cooling systems contend with added accessories such as, for example, automatic transmissions which have fluids that must be kept at safe temperatures and cabin heating systems. This is accomplished in a system which utilizes a radiator cap that can extend the coolant""s boiling point by less then 13xc2x0 F.
In the typical vehicle, the cooling system includes a water pump connected in the loop of the cooling system to drive coolant liquid through the engine. A thermostatic valve is mounted approximate the engine block to control the flow of liquid. The thermostat opens when the vehicle engine reached a selected temperature so that the liquid may circulate through the closed loop system and cool the engine. However, since a cold engine does not function properly, a normally operating thermostat remains closed and prevents circulation of cooling liquid until the engine heats to a desirable temperature range and then will subsequently open to allow circulation of cooling liquid.
Coolant liquid passes out of the engine, through the thermostat to a hose which connects the thermostat to the radiator. The radiator is metal and has a plurality of fins which absorb heat from heated coolant liquid. The fins dissipate the absorbed heat through air convection. By passing through the radiator, hot liquid from the engine is cooled and passes through an output hose back to the engine to again be heated while cooling the hot engine. As the engine runs and the vehicle moves, the cooling fluid is continuously circulated and re-circulated through the closed loop cooling system to keep the engine running at the proper temperature. A fan is disposed proximate the radiator to supply a convective stream of air therethrough when the vehicle is not moving.
In most vehicles, a heater core is located proximate the dashboard of the vehicle for receiving heated liquid from the engine in order to heat the vehicle cabin when necessary.
Checking a cooling system for proper operation is a time consuming, inaccurate and frequently inefficient process. Generally, after the engine is started and sufficiently warm, the radiator and thermostat are checked individually while the temperature of the vehicle is monitored to make sure that the engine does not overheat. In order to avoid possible damage to the engine from overheating, the mechanic doing the testing generally has had to pay close attention to the vehicle and engine while the cooling system was monitored for events such as opening of the thermostat. This is accomplished by an experienced mechanic feeling the radiator hoses as the vehicle warms up in order to monitor the system for changes in temperature and pressure. In marginal cases, accurate determinations using hand monitoring has not proved reliable. Consequently, mechanics tend to perform unnecessary repairs and replace parts such as thermostats and water pumps, as well as coolant, in hopes of guessing the cause of the problem.
In view of the aforementioned considerations, there is a need for a simpler and quicker method for testing a cooling system in order to determine the specific cause or causes of a malfunction.
A feature of the present invention is a new and improved method and apparatus for analyzing cooling systems of automotive vehicles in order to determine which components, if any, of the cooling system are malfunctioning.
With this feature and other features in mind, the present invention is directed to an apparatus for analyzing the cooling system of an internal combustion engine, wherein the engine includes a radiator, a thermostat coupled to the engine, a first hose connecting an inlet at the top of the radiator to the engine and a second hose connecting at the bottom of the radiator to the engine. A first sensor cable is connected to the first radiator hose and a second sensor cable is connected to the second radiator hose. The first and second sensor cables connect the sensors to first and second temperature measuring circuits which have outputs indicative of selected temperature levels. Temperature measuring circuits are connected to collators that serve as switches to apply the outputs of the first and second temperature measuring circuits to inputs of an array of logic circuits. The array of logic circuits have timing circuits connected thereto for providing time/temperature outputs to an array of indicators, wherein each indicator is associated with selected malfunction.
The present invention is also directed to a method of utilizing the aforedescribed apparatus.